Blaško Martin, Mach Pavel, Antušek Andrej, Urban Miroslav
Department of Physical and Theoretical Chemistry, Faculty of Natural Sciences, Comenius University , Mlynská Dolina, Ilkovičova 6, 842 15 Bratislava, Slovakia.
Department of Nuclear Physics and Biophysics, Faculty of Mathematics, Physics and Informatics, Comenius University , Mlynská Dolina, 84248 Bratislava, Slovakia.
J Phys Chem A. 2018 Feb 8;122(5):1496-1503. doi: 10.1021/acs.jpca.7b12232. Epub 2018 Jan 26.
Using DFT modeling, we analyze the concerted action of gold atoms and dispersion interactions in cross-linked polyethylene. Our model consists of two oligomer chains (PEn) with 7, 11, 15, 19, or 23 carbon atoms in each oligomer cross-linked with one to three Au atoms through C-Au-C bonds. In structures with a single gold atom the C-Au-C bond is located in the central position of the oligomer. Binding energies (BEs) with respect to two oligomer radical fragments and Au are as high as 362-489 kJ/mol depending on the length of the oligomer chain. When the dispersion contribution in PEn-Au-PEn oligomers is omitted, BE is almost independent of the number of carbon atoms, lying between 293 and 296 kJ/mol. The dispersion energy contributions to BEs in PEn-Au-PEn rise nearly linearly with the number of carbon atoms in the PEn chain. The carbon-carbon distance in the C-Au-C moiety is around 4.1 Å, similar to the bond distance between saturated closed shell chains in the polyethylene crystal. BEs of pure saturated closed shell PEn-PEn oligomers are 51-187 kJ/mol. Both Au atoms and dispersion interactions contribute considerably to the creation of nearly parallel chains of oligomers with reasonably high binding energies.
我们使用密度泛函理论（DFT）建模来分析交联聚乙烯中金原子的协同作用和色散相互作用。我们的模型由两条低聚物链（PEn）组成，每条低聚物链含有7、11、15、19或23个碳原子，通过C-Au-C键与一到三个金原子交联。在含有单个金原子的结构中，C-Au-C键位于低聚物的中心位置。根据低聚物链的长度，相对于两个低聚物自由基片段和金的结合能（BEs）高达362-489 kJ/mol。当忽略PEn-Au-PEn低聚物中的色散贡献时，结合能几乎与碳原子数无关，介于293和296 kJ/mol之间。PEn-Au-PEn中结合能的色散能量贡献随着PEn链中碳原子数的增加几乎呈线性上升。C-Au-C部分中的碳-碳距离约为4.1 Å，类似于聚乙烯晶体中饱和闭壳链之间的键距。纯饱和闭壳PEn-PEn低聚物的结合能为51-187 kJ/mol。金原子和色散相互作用都对形成具有相当高结合能的近乎平行的低聚物链有很大贡献。
